1. Technical Field
The present disclosure relates to an optical lens with an anti-reflection film and a lens module having the optical lens.
2. Description of Related Art
Lens modules may include at least one lens and a filter positioned at an image side of the lens. The filter may include a transparent substrate and an infrared filtering film formed on an object side of the transparent substrate. The filter is for reflecting infrared light rays while allowing the passage of visible light rays. However, about 5% or more of visible light rays are also reflected by the infrared filtering film. The reflected visible light rays form a glare in the image after multiple reflections in the lens module.
An anti-reflection film is formed on a surface of an optical lens of the lens module for reducing the glare in the lens module. FIG. 6, illustrates a reflection spectrum chart of a conventional anti-reflection film. The optical lens includes an optically effective portion and a peripheral portion surrounding the optically effective portion. Surfaces of the optically effective portion are generally spherical or aspheric surfaces. When the anti-reflection film is applied to the surface of the optical lens, the reflection spectrum chart of the anti-reflection film in the center region of the optically effective portion is different from that in the periphery region of the optically effective portion. FIG. 7, illustrates a reflection spectrum chart of the anti-reflection film formed on the optically effective portion of the optical lens. The solid line represents a reflection spectrum of the anti-reflection film in the center region of the optically effective portion, and the dashed line represents a reflection spectrum of the anti-reflection film in the periphery region of the optically effective portion. It is seen that, a reflectivity of the anti-reflection film in the periphery region of the optically effective portion is higher than 5% when a wavelength of light rays striking on the anti-reflection film are greater than 650 nanometers (nm), giving rise to glare during image capture.
Therefore, it is desirable to provide an optical lens with an anti-reflection film and a lens module having the same, which can overcome the limitations described.